Implementation of DMAIC methodology in green sand-casting process

Abstract

Foundry operations include many interrelated and complicated processes which are heavily dependent on the skills and potential of the operator. Depending upon the applications, various castings differ from their principal process parameters. Particularly in sand casting process, few process parameters are almost constant in each and every case, these are water content, bentonite content mixing time, etc. If the ratio and proportion of these parameters are altered, it will result into a casting defect. Many foundries are facing lot of rejections due to this reason. In this regard, it is therefore very important to equip the process knowledge by employing an appropriate methodology which uses defining, conceptualization and analysis of the process parameters to find the overall percent contribution of every parameter in a particular sand-casting process. Six sigma’s DMAIC methodology was implemented in a foundry in which major concern was to minimize the rejections. In this account four month’s data collected from a foundry and using quality tools three factors were considered as water content, bentonite content and mixing time to reduce defects in casting process. Taguchi approach was applied to create an orthogonal array. Experiments were performed as per L9 orthogonal array to obtain the response value of weight of casting and the hardness. Analysis of variance was also appraised to give the significance of the factors. Optimum levels were obtained which also validated by post experiment. In this paper feasible solution is provided to minimize the casting defects.